---
title: "InterestCharge – API-Referenz · Quittio"
description: "Default interest on an open amount for a period (simple interest)."
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> Index of every page on this site: [llms.txt](https://quittio.dev/llms.txt)

[API reference](https://quittio.dev/docs/api) / [Quittio](https://quittio.dev/docs/api/Quittio) \\ [Core](https://quittio.dev/docs/api/Quittio/Core) \\ [Documents](https://quittio.dev/docs/api/Quittio/Core/Documents)

# InterestCharge

final readonly class in quittio/core

`Quittio\Core\Documents\InterestCharge` · [Source](https://github.com/Quittio/quittio/blob/v0.7.1/packages/core/src/Documents/InterestCharge.php#L27)

Default interest on an open amount for a period (simple interest).

The period runs from $from (first day with interest, inclusive) to $until (exclusive): interest from 2026-02-01 until 2026-03-01 covers 28 days, the last day with interest is `lastDay()` (2026-02-28). Show lastDay() in texts, never $until.

Day count: by default actual/actual, i.e. the days of each calendar year are divided by the length of that year (365 or 366), so that a full year yields exactly the annual rate (section 288 BGB: "für das Jahr"). A fixed basis ($dayCount 365 or 360) divides all days by that number instead.

## Constants \#

| Constant | Value | Description |
| --- | --- | --- |
| `ACTUAL_ACTUAL` | `null` | Actual days divided by the length of each calendar year (365 or 366). |

## Properties \#

| Property | Type | Description |
| --- | --- | --- |
| `$amount` readonly | `?Brick\Money\Money` | |
| `$base` readonly | `Brick\Money\Money` | |
| `$dayCount` readonly | `?int` | |
| `$description` readonly | `?string` | |
| `$from` readonly | `[Date](https://quittio.dev/docs/api/Quittio/Core/Support/Date)` | |
| `$ratePercent` readonly | `Brick\Math\BigDecimal` | |
| `$until` readonly | `[Date](https://quittio.dev/docs/api/Quittio/Core/Support/Date)` | |

## Methods \#

| Method | Description |
| --- | --- |
| `->__construct()` | |
| `->days()` | Days with interest: from $from inclusive to $until exclusive. |
| `->lastDay()` | The last day with interest (the day before $until), for display. |
| `->total()` | Stated amount, or base × rate × days / day count basis, rounded half up once. |

### `__construct()`#

```
public function __construct(
    Money $base,
    BigDecimal $ratePercent,
    Date $from,
    Date $until,
    ?string $description = null,
    ?Money $amount = null,
    ?int $dayCount = self::ACTUAL_ACTUAL,
)
```

| Parameter | Type | Description |
| --- | --- | --- |
| `$base` | `Brick\Money\Money` | |
| `$ratePercent` | `Brick\Math\BigDecimal` | |
| `$from` | `[Date](https://quittio.dev/docs/api/Quittio/Core/Support/Date)` | |
| `$until` | `[Date](https://quittio.dev/docs/api/Quittio/Core/Support/Date)` | |
| `$description` | `?string` = `null` | |
| `$amount` | `?Brick\Money\Money` = `null` | |
| `$dayCount` | `?int` = `self::ACTUAL_ACTUAL` | |

### `days()`#

```
public function days(): int
```

Days with interest: from $from inclusive to $until exclusive.

<dl><dt>Returns</dt>
<dd><code>int</code></dd>
</dl>

### `lastDay()`#

```
public function lastDay(): Date
```

The last day with interest (the day before $until), for display.

<dl><dt>Returns</dt>
<dd><code><a href="https://quittio.dev/docs/api/Quittio/Core/Support/Date">Date</a></code></dd>
</dl>

### `total()`#

```
public function total(): Money
```

Stated amount, or base × rate × days / day count basis, rounded half up once.

<dl><dt>Returns</dt>
<dd><code>Brick\Money\Money</code></dd>
</dl>

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